The present invention relates to a refrigerant. Hydrochlorofluorocarbons, hydrofluorocarbons, azeotropic compositions thereof and like compositions are known as working fluids or refrigerants. Among them, R-11 (trichlorof luoromethane), R-12 (dichlorodif luoromethane), R-22 (chlorodifluoromethane), etc. have been conventionally used as working fluids for refrigerators. In recent years, however, it has been suggested that some hydrogen-free chlorofluorocarbons, when released into the atmosphere, would deplete the stratospheric ozone layer, thereby inflicting a serious adverse influence on the ecosystem including humans on the earth. In view of the problem, a worldwide agreement calls for the restriction of use and production of major ozone-depleting chlorofluorocarbons. Among the chlorofluorocarbons to be controlled for the restriction are R-11, R-12 and the like all of which are widely used as mentioned above. With the spread of refrigerators and air-conditioning systems, the use and production of these refrigerants are enjoying an annually increasing demand. However, the control over these refrigerants will greatly affect our residential environments and the current social framework as a whole. Consequently, there is an urgent demand for development of a novel refrigerant which has no or little potential to cause the problem of depleting the stratospheric ozone layer.